Power Antenna

My father has a 87 G/A and his power antenna works but doesn't go up or down all the way sometimes. He's been driving me nuts about this cuz he keeps cleaning it with rubbing alcohol, and spraying silicon spray on it. :banghead: Now this helps for about 3 days before it goes back to the way it was. I personally think this is very bad for the antenna, But he fails to listen to me. My question is there a special lubricant I should be using on the antenna so we DON"T have this problem. Of all the things he's concerned about, he worries about the antenna, not the oil leak, or various other problems with this rare G/A, ( btw my fathers 87 G/a is a rare car since I've only found 1 other Similar to it, but he seems to not care that the car is rare. :rolleyes:) ANY help to get him off my back will be appreciated.